Electric meter



W. C. WAGNER ELECTRIC METER Oct. 22, 1940.

Filed June 5, 1957 4 sheets-sheet las l Q S www w. c. WAGNER ELEC-TRIOMETER 4 Sheets-Sheet 2 Filed June 5, 1957 5y @uw @ESM ,WM/1n fram/EXOCt. 22, 1940. W, Q WAGNER v2,218,663

ELECTRIC METER I Filed June I5, 1957 4 Sheets-Sheet E Y WQ//efCLV/142577262" @SWW Patented Oct. 22,1940 f a UNITED ySTTES PATENTOFF-ICE e ELECTRIC METER A i u Walter (XWagner, Ardmore, Pa. nApplication June 3, 1937, serial No.l 146,209 y v1o claims. (cigni- 264)This invention relates to electric meters and my invention embodies awatthour meter'corn more particularly relates to integrating metersnested in the secondary circuitof ay transformer for measuring energytransmitted by the highand adapted to measure theenergy in thepritension circuit of a powertransformer Aor transmary circuit of saidtransformer, said meter informers with the meter connected in thelow-tencludingV a voltage-squared-hour element or the 55 sion circuitleading therefrom. equivalent to increase the yregistration by anMeasurement of electric energy in the low-tenamount proportional to thatpart of the core loss sion circuits of power transformers to include theof said transformer which 'cannot be compensated energy dissipated inthetransformer and/or in for bythe use of the customary adjusting devicesthe associated electric conductors and equipment o fa standardwatthourmeter. l has the advantage over high-tension lmetering My invention,both as to details of construction equipment in that capital andl'operating costs are and'COmbineftiOn 0f Perils, .Will be heierlindergreatly reduced, space is conserved, personal hazstood from thefollowing description of specific ards incident to line and meteringoperation and embodiments, when read in Connection with the 5maintenance are reduced, and vulnerability of the accompanying-fllalWingS, in WhiCh 15 metering equipment to damage lby high-tensionlFig. lis a diagrammatical view of one'form of and lightning surges, andconsequent service inmy invention, and the circuit connections thereto.terruptions, are minimized. Fig. 2 is a diagrammatical view showing amod- Energy dissipated in power transformers can ication of myinVenliiOIL beconsidered as composed of core losses and copf Figs. 3 and4 are dagremmalieel VieWSShOWing 20 50 an improved meter which, whenconnected in the having the characteristics of a potential electro-v perlosses. The core losses, for given frequency further modifications of myinvention. and wave form, vary approximately as the square l Figs. 5, 6and 9 are diagramma-tical VieWS ShOW- of the voltage. The copperlossesin the transins filrther modeatons of my invention emformer andassociated yelectric l conductors rand DlOying the InOdifiCerl'fiOnShOWn in Fig 4- equipment are directly. proportional to the square Figs.'l 'and 8 are diagrammatical views showing 2.5 of the load current. vfurther modifications of my invention employing By means of thecustomary adjusting device, the Inediealion Shown in Fig.r 1- theregistration of a standardy wattnour meter .Similar numbers refertesimilar parts throughconnected in the secondary circuit of a transeilttheseveralviews. V A former can be changed from .that of the output InFie. 1 the top element is, a 'standard Watt- 30 of the transformer by anamount corresponding hour' ymeter element which includes a current tothe sum of the copper losses concerned at any eleetrmeggneif l0 inSefieSWith ihe'leed Current, load andthe coreV 105s of .the transformer overa-potential electromagnet Il connected across the part of the meter loadrange. vA watthour meter line; and a disk l2 which isjmounted on a'shaftwhose registration is so modied can therefore l?, suitably geared t0af-Iegistel' I4 in the 6115130111- 35 be used in the` secondary' circuittol measure enary manner) This element includes` the usual ergytransmitted by the, primary circuit of the full-load adjusting devices4l; light-load adjusttransformer, provided extreme `accuracy at all ingdeViCeS 42, and deDhaSing Coils 43- The meter points of the meter load`ramgek is not required. is connected between a transformer I1 'and load40 The particular Ydefect of this method of meter- I6 and is -containedin the housing OI' Casing |00, 40 ing is that the errors of registrationincrease with Lead vl ll enneCS With Potentiel @Oil l While decreasingload and are extremely high at zero lead `I I0 connects 'with currentcoil l0. vLead II2 transformer load.` In certain cases, transformersconnects current coil I0 with load I6 While lead may be operated forlong periods at Very light or H3 connects potential coils II-and 2| `andelecno load and such errors become' important in the tromagnet 20 havingthe characteristics of a cur- 45 total meter registration. l Y rentelectromagnet with transformer '-I'I.

The principal object of'my'invention is to'pro- :The lower element ofFig; v1v comprises an duce a meter in which these defects are overcome.electromagnet 20l having the characteristics of a Another objectof my'invention is 'to' provide current electromagnet, and an electromagnet 2l50 secondary circuit of a transformer, will measure magnet, bothoperating on a disk 22 also connectwith accuracy the energy transmittedby the pried to shaft I3. The potential electromagnet 2| mary circuit ofsaid transformer. is a standardfwatthour meter potential electro- Withthese andlrelated objects in view which magnet and is connected acrossthe line. The

5 will become apparentasthedescrption proceeds, -.current.electromagnet2E in series with an adjustable resistor 23 is connected across theline. This element, therefore, has the torque characteristics of avoltage-squared-hour-meter element.

The calibration of my meter for use with any designated transformer isperformed as follows:

With no currentvowing through electromagnet I0 and with electromagnet IIconnected across the line, resistor 23 is adjusted to produceregistration of the predetermined core loss. The meter is thencalibrated at various loads in the customary manner except thatadjustments are made so that the meter registration at the selectedloads is increased by calculated values corresponding toV the core andcopper losses of the transformer for transformer secondary loadingsequal to the selected loads.

Fig. 2 shows a modification which is a functional equivalent of thedevice of Fig. 1. In this device the voltage-squared-hour component ofthe-torque imparted to the shaft I3 is produced in the single disk I2 byinteraction of the electromagnetic eiects of an auxiliary winding 30 andthe ordinary potential electromagnet |I of a Watthour meter. Winding30,. which has the characteristics of a current electromagnet, issuperposed upon the poles of winding Ill, or wound at any convenientlocation upon the magnetic structure of which these poles form a part,and is connected in series with adjustable resistor 23 across the line.The remaining parts of this modication are an ordinary watthour meterelement as illustrated in Fig. 1. l

Fig. 3 illustrates another modification of my invention. The top element24 is a standard watthour meter element which includes a currentelectromagnet I0, a potential electromagnet I I, a disk I2 attached to ashaft I3 which is suitably geared to the register I4 to register theelectric energy supplied toy load I6 from the secondary of transformerI'I, and the customary watthour meter adjusting devices 4|, 42 and 43.

The bottom element 27 of Fig. 3 includes an electromagnet 2|, having thecharacteristics of a potential electromagnet, and an electromagnet 30A,having the characteristics of a current electromagnet, both' operatingon a disk 22 also attachedto shaft I3. The potential electromagnet 2|and the current electromagnet 30A in series with an adjustable resistor23 are connected across the line. Electromagnets 2| and 30A, comprisinga voltage-squared-hour element, cooperatively produce in disk 22 atorque which may be adjusted by means of resistor 23 to causeregistration of the desired transformer core loss. Although the usualfriction-compensating or lightload VadjustingV device of a standardwatthour meter may be adjusted to produce a torque of the nature of avoltage-squared torque, the range of adjustment is generally inadequateto cause increase of registration equivalent yto the core loss `of powertransformers. On the other hand, the winding 30A provides a truevoltage-squared torque with as great a rangeof adjustment as desired.

A current electromagnet 40, which may consist of relatively few turns ofheavy wire, is connected'in series with the load I6 and is so woundthatV its magnetic influence opposes the torque created in disk 22 bythe coaction of electromagnets 2| and 30A.` At some definite load, thecountertorque producedby winding 46, which is proportional to the load,exactly cancels the coreloss torque produced by electromagnets 2| and30A, and element. 2l then does not add. to vthe registration of element24. The magnetic circuits of the current electromagnets are designed toobtainA magnetic saturation substantially when the resultant torque ofelement 27 is Zero by means of an adjustable part 4| to alter thecrosssectional area of a part of the core or by other means. Furtherincrease in current through winding lill may produce additional negativetorque and damping. .These are relatively small and yproportional to theload and may therefore be compensated for by the customary full-loadadjusting device oi the watthour element 24.

The calibration of the meter illustrated in Fig. 3 for use in thesecondary circuit of any designated transformer to measure primaryenergy is performed as follows:

With no current flowing through windings 30A and 4) of element 2l, andwith potential electromagnets II and 2| energized, the standard watthourelement 24 is adjusted, by the customary means, to register thetransformer primary energy corresponding to the usual meter calibrationpoints. Then, with no current flowing through series windings IQ and 4D,and with potential electromagnets II and 2| energized, the

current electromagnet 38A of element 21 is adjusted, by means ofresistor 23, to produce meter registration Vcorresponding to thepredetermined core loss. Sufficient current is then passed throughelectromagnet 40 to produce a counter- `torque to cause shaft I3 tocease rotating. The

characteristics of coil 40 ,are such that the magnitude of currentrequired to produce this effect is of the order of a few per cent ofnominal current rating of element 24. The core of electrof" countered inthe measurement of core losses and c loads of the same order, it isadvisable in some cases to employ disks without the usual anticreepholes in my improved meter.

Although illustrated and described hereinbefore as being connecteddirectly into and to electric conductors leading from the transformersecondary, my improved meter may be Used also in conjunction withinstrument transformers whenever the characteristics of the powercircuits to be metered make such procedure advisable.

One way of doing this is shown in Figs. 4 and 5 in which my device isshown as consisting of two standard watthour meter elements and 5I.Element 5I! shows a current coil I0 connected into the circuit by leads2|0 and 2| I, and a potential coil II connected across the circuit byleads 2|2 and 2I3, respectively. Element 5I consists of acurrent coil|0A connected into the circuit by leads 2|4 and 2| 5, anda potentialcoil connected across thev circuit by leads 2I6 and 2I'I, respectively.Elements 5U and 5| co-operate with disks I2 and IZA, respectively. DisksI2 and IZA are both mounted on shaft I3 which drives register I4.Elements 5|] and 5I contain the customary watthour meter-adjustingdevices 4I, 42, 4|A and 42A, respectively. This meter also includes a'third element 53 similar to the lower element of Fig. l and having'apotential coil 2| connected across the circuit by leads ZIB and 2I9, andan electromagnet 20 having the characteristicsof a currentelectromagnet, both operating on a disk 122 also connected to shaft I3.The current electromagnet 20 is'in series with an adjustable resistor23v across the line, being connectedto leads 2I8 and 2I9. TheA entiremeter is` located in a housing or casing I0 I.

Asi seen'in Fig. 5, the meter shown in Fig. 4 is connected across athree-phase, three-Wire circuit having a polyphase transformer I1A andpotential transformers |02 and current transformers |03 and load IGA.The leads bear the same reference characters as in Fig. 4.

Myinvention is not limitedto the single-phase form hereinbeforerepresented except in Figs. .4 and 5, butmay, bythe addition of asuitable number ofl elements, be adapted to meter .polyphase circuits.

One example of this is shown in Fig. 6 in which the meter shown in Fig.4 is connected into a two-phase, four-wire `circuit having polyphasetransformers I'IB and current transformers |03A and load ISB. As will beseen from a comparison of Fig. 5, the meter is connected into thecircuit by means of the leads as shown in Fig. 5 except that the lead2II shown in Fig. 5, instead of being connected to the lead 2I3,lisreplaced by a lead 2I'IA leading directlyr to one side of the maincircuit on the input side of the current transformers I03A.

Fig. 7 shows another way-in which my invention is adapted to meterpolyphase circuits. In this modification, three of the meters shown inFig. 1 are connected into a three-phase, four-wire circuit havingpolyphase transformers I'IC` and load IGC but without current orpotential transformers. The leads III), lIII, II2 and II3 connect to themeter elements through the casings IMI exactly as shown in Fig. 1.

Although in the foregoing description my invention is referred to asapplied to the measurement of active energy only,-it is equallyapplicable to the measurement of reactive components of load.

Just as electric power of a single phase load is the product of thecircuit Voltage, current and the cosine of the phase angle between them,the reactive component is the product of the voltage,

currentv and sine of the phase angle. Hence, if

the potential element of a standardwatthour -meter be supplied with avoltage in phase quadrature with the circuit voltage, the meter willmeasure the reactive component of the load. In single-phase circuitsthis quadrature potential is customarily obtained by a combination ofresistance and reactance, in two-phase or quadrature circuits bycross-connecting the potential coils to opposite phase wires from thosein which the corresponding current coils are connected, and inthree-phase circuits by the use of special phasing transformers and/orreactors. Fig. 8 shows the connections for measuring the reactivecomponents of load in a two-phase three-wire circuit, using two of themeters shown in Fig. 1. VThis circuit has a polyphase transformer I 1Dand a load ISD. Meters similar to those shown in Fig.

1 are connected into this circuit by leads I I0, I I I, I I2 and I I3connected internally in the same way as those shown in Fig. 1. It willbe noted that for each meter the potential coils are energized from onevphase and the current coil from the other, thus accomplishing thecross-phase connection.

The procedure for calibrating my meter for the 1 measurement of reactivecomponents of load supplied through any designated transformer plus thereactive componentofcore loss of saidv transformer is the same as forthe previously'describedcalibration of my meter for active componentmeasurements, except that the adjustments are .made to produce meter.registration proportional `to the predetermined magnitude of thereactive componentsat the average voltage of the circuit' to bemeasured. l

Another method of measuring reactive components of vload is illustratedin Fig. 9 in which the meter shown in Fig. 41s connected into atwophase, three-wire circuit having polyphase trans'- former I'IE andload ISE.. The leads bear the same reference characters as those inFigs. 4 and 5 and connect inside the casing IGI to similar` meterelements as in said-Figs. 4 and 5. 'I'he connections shown in Fig. 9 aresimilar to those shown in Fig. 8, the essential diierence between Figs.8 and 9' being the replacement of the separate-meters in Fig. 8 by theirpolyphase equivalent in Fig. 9. This means rthat whereas each lowerelement in the meters represented in Fig. 8 contributes torqueproportional to the vreactive component-of the core loss of thetransformer phase supplyingthe phase to which the particular element isconnected, the lower element of Fig. 9 contributes a torque.proportionalto the reactive component of the total core loss of thetransformer bank. Furthermore, the summation Vvof phase measurements isautomatically registered'on a single set of dials in Fig. 9 obviatingthe necessity of adding the readings of separate meters as in Fig. 8. vMy invention in any of the forms suitable for metering energy, specificembodiments of which are illustrated in Figs. 1 to '7, inclusive, issuitable for metering either reactive or unity power' factor loads',Vcalibration therefor being made as in customarymetering practice. v

It will be obvious to those skilled in the art to which ther inventionrelates that modications may be made in details of construction andarrangement without departing from the spirit of the invention which isnot limited in respect to such mattersl or otherwise than as the priorart and the appended claims may require.

AI claim: v f 1. In a standardwatthour` meter connected between atransformer and ai load and havingv adjustmentsfor compensating'forthecore losses and for the copper losses of said transformer so as tomeasure the'power fed to said transformer,

an additional element for causing said meter to y indicate inresponse tothe square of the voltage applied to said element, and means foradjusting the Voltage applied to said elementto the amount representingthefcore losses in said transformer.

2. In a standard'watthour meter connected bev tween a transformer and aload and having adjustments for compensating for the core losses and forthe copper losses of said transformer so as to measure the power fed tosaid transformer, a metal disk connected to the movable element of saidmeter,two coils mounted in operative relationto said disk and eachconnected across said transformer and across said load, and anadjustable resistance connected in series with one of said coils acrosssaid transformer and across said load.

3. In a standard watthour meter connected between a transformer and aload, the combination of, a metal disk, a current coil arranged to movesaid disk proportionately to the currentpassing throughv said meter tosaid load, a potential coil arranged to move said disk proportionatelyto the voltage 'applied to the meter .and tclsad load, a coil inelectromagnetic relation to said disk and to .said current coilA andarranged to move said .disk proportionately to the square of the voltageapplied to said coil, andmeans for adjusting the 'voltage applied tosaid last-mentioned coil to the amount representing the core losses inthe transformer.

4. In a standard Watthour meter connected in the secondary circuit of apower transformer and adjusted as nearly as possible for the measure--ment of the energy transmitted in the high-ten- :sion circuit of thetransformer, a voltagesquared-hour element for increasing the drivingA,torque of the meter by an amount proportional :to that part of thecore loss of said transformer which kcannot be compensated for by theuse of ythe standard `adjusting devices of said meter.

5. For adjusting a standard Watthour meter to increase its registrationby an amount corresponding to transformer core losses lwhich vary as theSquare of the voltage, means coacting with :said standard Watthour metercomprising anl elementphaving the `characteristics of current andvoltage elements and adapted to generate magnetic lines of force, and anelement having the characteristics of a voltage element and adapted togenerate other magnetic lines of force and operative upon said lines vofforce to increase the torque by the product of said magnetic lines ofiorce, which `gives rise to the voltage squared.

6. In a Wa-tthour meter having the customary current and potentialelectromagnets and a yoke -a-nd a disk With an yair-gap between them, acoil lin addition to said electromagnets having the characteristics of acurrent electromagnet, a variable resistor, said coil in series withsaid variable resistor being connected in multiple with said potentialelectromagnet, and said coil .being arranged on the yoke of said meterto produce asymmetry of magnetic flux distribution in the ydisk air gap.f

7. In an electric Vvvatthour meter connected to the secondary of atransformer and arranged to register the power supplied to the primaryof the transformer, a rst standard Watthour element, a second standardWatthour element and having a friction compensating or light loadadjusting device and having*y a current electromagnet, a

single shaft arranged for rotation by said elements, the frictioncompensating or light load adjusting device of said second element beingadjusted to counteract the core loss at vno load and thecurrentelectromagnet of said second element being connected in series with theload so that its magnetic influence opposes the torque of said rstelement, and means to produce magnetic saturation of the core of saidcurrent electromagnet at :loads greater than that at Which the resultanttorque of said second element is zero.

8. In a Watthour meter, a register, a standard Watthour meter elementhaving a potential `coil yand a current coil, an auxiliary specialWatthour meter element having a potential coil and a current coil Woundin magnetic relation and imparting a voltage squared component of torqueby interaction of their electric magnetic eiects,

an auxiliary Winding connected in series with the current coil of thestandard element and imparting a retarding torque to said auxiliaryelement, anda single shaft arranged for rotationA by said elements andconnected to said register to drive it.

9. In a standard vvatthour meter connected between a transformer and aload, la register, a standard watthour meter yelement having a potentialcoil and a current coil and adjusted for registration of the primaryenergy at the selected meter loadings, an auxiliary. special Watthourmeter element having a potential coil and a cur rent coil Wound inmagnetic relation and imparting a voltage squared component of torque byinteraction of their electric magnetic effects, an auxiliary Windingconnected in series with the current coil of the standard element andimparting a retarding torque to said auxiliary element, a single shaftarranged for rotation by said elements and connected to said register todrive it, and means to produce magnetic saturation of the core of saidauxiliary electromagnet.

10.. In combination with a standard watthour meter element having a.magnetic ux circuit with an air-gap therein and a `disk in said circuitand in said air-gap, a coil in addition to the electromagnets of saidmeter and having the characteristics of a current electromag'net andhaving impedance adjusting means, said coil being connected in multiplewith the potential velectromagnet of said meter, and -being arranged inthe magnetic flux circuit of said meter to produce asymmetry of fluxdistribution in the disk air-gap of said meter.

WALTER C. WAGNER.

